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1st grade math · Unit 1: Adding and subtracting within 20

How many were added?

What this lesson shows

Trevor had 16 cars and now has 20: 16 + ? = 20.

The worked example

The lesson works this one step by step: 16 cars, now 20. Then your kid tries one like it on paper.

The steps

  1. A box for the change
  2. Draw more up to the total
  3. Count the new ones

Helping at home

Write the story with a box for the number you do not know. Draw what you start with, then draw more until you reach the end number. Count the new ones.

If your kid gets stuck

Draw more until you reach the total.

Watch it with Lux

With Lux, this lesson is a narrated video and a printed page your kid works on. Then Lux helps with the same math on their own worksheet, one question at a time.

See how Lux works

Standards

  • Common Core 1.OA.A.1
    Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.
  • Common Core 2.OA.A.1
    Use addition and subtraction within 100 to solve one- and two-step word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem.
Matches a standard in all 50 states and DCSee each state's code

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